HORTICULTURE. 745 



this method ^or the production of nonastringent porsiunuons which may be 

 pared and eaten lilce au apple. 



[Artificial ripening of dates] (An:;oiJa Sta. Bui. 66, pp. -'i03--^56, pi. 1, figs. 

 fj).— After worlving with the date palm for a number of years and having 

 brought under control for the most part the active enemies of the palm, the 

 Arizona Station finds that the excessive waste due to insects, birds, and un- 

 timely wet weather remains a most serious drawback to the natural ripening 

 of the fruit, as high as 90 per cent of the crop having been lost during un- 

 favorable seasons. This, together with the almost complete failure of the 

 Deglet Noor date, which is the standard of excellence in the Sahara, to mature 

 and ripen naturally under Arizona conditions led to an attempt to devise a 

 rational method of artificial ripening. Two i)rocesses of artificial ripening 

 have been worked out. by the perfection and commercial adoption of which it 

 is believed the loss of fruit will be almost wholly saved. 



Chemistry and ripening of tlie dote, by A. E. Vinson (pp. 40.S^35). — The 

 author has continued his studies of date ripening and its economic application 

 previously noted (E. S. R., 19. p. 22; 20, pp. 64, 6.59; 23, p. 641). The present 

 report summarizes his investigations relative to date chemistry, including the 

 phenomena of natural and artificial rii>ening and the development of a suc- 

 cessful method of ripening dates through stimulation by chemicals at ordinary 

 temperatures. Brief consideration is also given to the practical application of 

 this method and its commercial importance. The results of more immediate 

 practical application are summarized as follows: 



" During the early period of its growth the date does not differ materially 

 from other nonstarchy fruits in the percentage of dry matter it contains. 

 After apparent maturity in size the rapid accumulation of sugar begins. This 

 continues till the date begins ripening. It is thus desirable, even if artificial 

 ripening is to be practiced, to leave the fruit on the tree as late as possible. 

 If cut too early, the flesh about the see<l must necessarily be thin and insipid. 

 " Some varieties of dates begin ripening when they contain not more than 

 55 or 60 per cent of dry matter. Their sugar content is not quite high enough 

 to make them self-curing without further concentration of the juice. This 

 does not occur in humid weather, and fermentation soon starts which further 

 lowers the sugar content until the dates sour rapidly. Other varieties begin 

 to ripen only after a much higher percentage of sugar is present and conse- 

 quently are sugar cured before the protection of the living tissue of the unripe 

 date is broken down by ripening. These differences determine souring and 

 curing varieties. 



" After dates have reached sufficient maturity they may be ripened artificially 

 either by heat or by chemical stimulation. The naturally ripened dates have 

 a delicate aroma which vanishes rapidly in the case of some varieties and per- 

 sists for many days with others, notably Deglet Noor. This aroma is not 

 developed by heat ripening. Many varieties ripen quickly after treatment with 

 various chemicals, of which acetic acid is the best in most cases. They may 

 be treated with the vapor of the strong acid or soaked a short time in vinegar. 

 Those that ripen after this treatment develop the aroma of the naturally 

 ripened fruit. Less responsive varieties, as Deglet Noor, yield i-eadily to the 

 vapor of nitrous ether, which is effective in exceedingly small amounts. It does 

 not destroy the flavor and only slightly deepens the color. 



" By the application of chemical methods of stimulating ripening, it will 

 probably be possible to ripen inferior varieties, which deteriorate rapidly, at 

 distant markets, and so to time the process that they may be delivered to the 

 consumer in their best condition. This process may make possible the use 

 of varieties which can be grown successfully under a wider range of climatic 

 conditions than the Deglet Noor." 



